solar

306 Articles

Damn Fine (Solar Powered) Coffee

November 19, 2025 by 30 Comments

The folks at Low Tech Magazine are here again, this time with a solar powered coffee maker. Lest you think of a large parabolic mirror with a pot at its focus, in this case the device is much more friendly. It’s a table-top appliance that relies upon a 100 W, 12 V panel for its operation.

They make the point that an electric coffee pot requires at least 300 W to work, so what’s the secret? In this case, insulation, as a standard moka pot is placed within a nichrome heating element set in mortar and surrounded by cork. On the outside are tiles, though they appear largely ornamental and the write-up suggests you could experiment with other materials to serve as an enclosure.

It appears to be an effective coffee maker, with the significant caveat that it’s hardly fast. In full sunlight the first pot takes over an hour to brew, with subsequent ones once it’s up to temperature being somewhat faster. But you can’t argue with the idea of free power, even if your favourite caffeinated beverage may now take a while to appear.

We like this idea, despite its slow brewing. We’ve featured Low Tech Magazine before, not least in their solar powered oven.

Ask Hackaday: When Good Lithium Batteries Go Bad

October 20, 2025 by 65 Comments

Friends, I’ve gotten myself into a pickle and I need some help.

A few years back, I decided to get into solar power by building a complete PV system inside a mobile trailer. The rationale for this doesn’t matter for the current discussion, but for the curious, I wrote an article outlining the whole design and build process. Briefly, though, the system has two adjustable PV arrays mounted on the roof and side of a small cargo trailer, with an integrated solar inverter-charger and a 10-kWh LiFePO4 battery bank on the inside, along with all the usual switching and circuit protection stuff.

It’s pretty cool, if I do say so myself, and literally every word I’ve written for Hackaday since sometime in 2023 has been on a computer powered by that trailer. I must have built it pretty well, because it’s been largely hands-off since then, requiring very little maintenance. And therein lies the root of my current conundrum.

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Multi-Use Roof Eliminates Roof

September 11, 2025 by 57 Comments

One of the biggest downsides of installing solar panels on a rooftop is that maintenance of the actual roof structure becomes much more difficult with solar panels in the way. But for many people who don’t have huge tracts of land, a roof is wasted space where something useful could otherwise go. [Mihai] had the idea of simply eliminating traditional roofing materials altogether and made half of this roof out of solar panels directly, with the other half being put to use as a garden.

Normally solar panels are installed on top of a roof, whether it’s metal or asphalt shingles or some other material, allowing the roof to perform its normal job of keeping weather out of the house while the solar panels can focus on energy generation. In this roof [Mihai] skips this step, having the solar panels pull double duty as roof material and energy generation. In a way this simplifies things; there’s less to maintain and presumably any problems with the roof can be solved by swapping out panels. But we would also presume that waterproofing it might be marginally more difficult.

On the antisolar side of the roof, however, [Mihai] foregoes the solar panels in favor of a system that can hold soil for small garden plants. Putting solar panels on this side of the roof wouldn’t generate as much energy but the area can still be useful as a garden. Of course we’d advise caution when working on a garden at height, but at least for the solar panels you can save some trips up a ladder for maintenance by using something like this robotic solar panel scrubber.

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A fisheye lens picture over the Junma Solar Power station in the Mongolian desert. There is a large image of a horse made out of solar panels in the image. A sunset is visible in the upper right of the image, but most the picture is brown sand where there aren't dark blue solar panels.

China’s Great Solar Wall Is A Big Deal

August 18, 2025 by 60 Comments

Data centers and the electrification of devices that previously ran on fossil fuels is driving increased demand for electricity around the world. China is addressing this with a megaproject that is a new spin on their most famous piece of infrastructure.

At 250 miles long and 3 miles wide with a generating capacity of 100 GW, the Great Solar Wall will be able to provide enough energy to power Beijing, although the energy will more likely be used to power industrial operations also present in the Kubuqi Desert. NASA states, “The Kubuqi’s sunny weather, flat terrain, and proximity to industrial centers make it a desirable location for solar power generation.” As an added bonus, previous solar installations in China have shown that they can help combat further desertification by locking dunes in place and providing shade for plants to grow.

Engineers must be having fun with the project as they also designed the Guinness World Record holder for the largest image made of solar panels with the Junma Solar Power Station (it’s the horse in the image above). The Great Solar Wall is expected to be completed by 2030 with 5.4 GW already installed in 2024.

Want to try solar yourself on a slightly smaller scale? How about this solar thermal array inspired by the James Webb Telescope or building a solar-powered plane?

Linear Solar Chargers For Lithium Capacitors

June 26, 2025 by 24 Comments

For as versatile and inexpensive as switch-mode power supplies are at all kinds of different tasks, they’re not always the ideal choice for every DC-DC circuit. Although they can do almost any job in this arena, they tend to have high parts counts, higher complexity, and higher cost than some alternatives. [Jasper] set out to test some alternative linear chargers called low dropout regulators (LDOs) for small-scale charging of lithium ion capacitors against those more traditional switch-mode options.

The application here is specifically very small solar cells in outdoor applications, which are charging lithium ion capacitors instead of batteries. These capacitors have a number of benefits over batteries including a higher number of discharge-recharge cycles and a greater tolerance of temperature extremes, so they can be better off in outdoor installations like these. [Jasper]’s findings with using these generally hold that it’s a better value to install a slightly larger solar cell and use the LDO regulator rather than using a smaller cell and a more expensive switch-mode regulator. The key, though, is to size the LDO so that the voltage of the input is very close to the voltage of the output, which will minimize losses.

With unlimited time or money, good design can become less of an issue. In this case, however, saving a few percentage points in efficiency may not be worth the added cost and complexity of a slightly more efficient circuit, especially if the application will be scaled up for mass production. If switched mode really is required for some specific application, though, be sure to design one that’s not terribly noisy.

Adaptive Optics Take Clearest Pictures Of The Sun Yet

June 1, 2025 by 9 Comments

It’s sometimes easy to forget that the light in the sky is an actual star. With how reliable it is and how busy we tend to be as humans, we can take that incredible fact and stow it away and largely go on with our lives unaffected. But our star is the thing that gives everything on the planet life and energy and is important to understand. Humans don’t have a full understanding of it either; there are several unsolved mysteries in physics which revolve around the sun, the most famous of which is the coronal heating problem. To help further our understanding a number of scientific instruments have been devised to probe deeper into it, and this adaptive optics system just captures some of the most impressive images of it yet.

Adaptive optics systems are installed in terrestrial telescopes to help mitigate the distortion of incoming light caused by Earth’s atmosphere. They generally involve using a reference source to measure these distortions, and then make changes to the way the telescope gathers light, in this case by making rapid, slight changes to the telescope’s mirror. This system has been installed on the Goode Solar Telescope in California and has allowed scientists to view various solar phenomena with unprecedented clarity.

The adaptive optics system here has allowed researchers to improve the resolution from the 1000 km resolution of other solar telescopes down to nearly the theoretical limit of this telescope—63 km. With this kind of resolution the researchers hope that this clarity will help shine some light on some of the sun’s ongoing mysteries. Adaptive optics systems like this aren’t just used on terrestrial telescopes, either. This demonstration shows how the adaptive optics system works on the James Webb Space Telescope.

Thanks to [iliis] for the tip!

Jettison Sails For Electric Propulsion

May 21, 2025 by 32 Comments

Although there are some ferries and commercial boats that use a multi-hull design, the most recognizable catamarans by far are those used for sailing. They have a number of advantages over monohull boats including higher stability, shallower draft, more deck space, and often less drag. Of course, these advantages aren’t exclusive to sailboats, and plenty of motorized recreational craft are starting to take advantage of this style as well. It’s also fairly straightforward to remove the sails and add powered locomotion as well, as this electric catamaran demonstrates.

Not only is this catamaran electric, but it’s solar powered as well. With the mast removed, the solar panels can be fitted to a canopy which provides 600 watts of power as well as shade to both passengers. The solar panels charge two 12V 100ah LifePo4 batteries and run a pair of motors. That’s another benefit of using a sailing cat as an electric boat platform: the rudders can be removed and a pair of motors installed without any additional drilling in the hulls, and the boat can be steered with differential thrust, although this boat also makes allowances for pointing the motors in different directions as well. 

In addition to a highly polished electric drivetrain, the former sailboat adds some creature comforts as well, replacing the trampoline with a pair of seats and adding an electric hoist to raise and lower the canopy. As energy density goes up and costs come down for solar panels, more and more watercraft are taking advantage of this style of propulsion as well. In the past we’ve seen solar kayaks, solar houseboats, and custom-built catamarans (instead of conversions) as well.

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